Electronic Enclosures: Types, Design Requirements and Benefits

Chapter 1: Understanding Electronic Enclosures Principles

This chapter will delve into the concept of electronic enclosures and outline the steps involved in their creation.

Defining Electronic Enclosures

Electronic enclosures are protective housing units, designed to safeguard electronic components like switches, relays, printed circuit boards (PCBs), integrated circuits, power sources, and processors. These enclosures are available in a variety of materials and sizes, customized to fit their intended use, purpose, operational environment, and budgetary limits. The diagram below showcases an electronic enclosure providing protection to its inner components.

Imagine an electronic device susceptible to water infiltration, accessible to children, or exposed to heat and damp conditions. Such devices could incur harm from environmental factors and present safety risks to users. To solve these problems, engineers specializing in electronics and electrical systems have created protective casings that guard against environmental exposure and other dangers linked with unprotected components, known as electronic enclosures.

The Role of Metal Boxes

A metal box is a well-designed container for sheltering, storing, and enclosing items. Aluminum and stainless steel enclosures are classified as metal boxes. Often employed as fuse boxes and outdoor electrical meter boxes, metal boxes are also utilized in business environments to encase electrical devices that supply power across the premises.

In industrial environments, electronic enclosures safeguard sensitive components from accidental impacts, debris, contamination, and dirt. They minimize damage from workplace accidents involving workers or machinery, thereby lowering the chances of severe issues like explosions or electrical failures.

The International Electrotechnical Commission (IEC) offers guidelines for selecting suitable enclosures and ratings based on their intended application. For instance, metal enclosures in telecommunications must be carefully chosen to prevent disruption or interference with information transmission. Choosing an inappropriate enclosure type can result in significant operational setbacks.

The Manufacturing of Electronic Enclosures

Several techniques are commonly employed in crafting electronic enclosures, as detailed below.

CNC Machining

Computer Numerically Controlled (CNC) machining applies subtractive processes where a machine interprets CAD files to precisely guide a cutting tool. This allows precision cutting according to the specifications outlined in the CAD designs.

This process on CNC machines can be repeated as long as the program files remain accessible. This is beneficial as the same program used to create a plastic enclosure can also be used for a metal enclosure. CNC machining is ideal for producing intricate geometric designs.

Sheet Metal Fabrication

Sheet metal fabrication transforms flat metal sheets, usually aluminum or steel, into metallic formations through folding and assembly processes. This method is a cost-effective and efficient solution for making electronic enclosures. Compared to CNC machining, it is usually quicker and less complicated.

Commonly used for crafting both outdoor and desktop electronic enclosures, this method's cost per part significantly drops with increased production, despite a high initial investment in sheet metal fabrication equipment.

Injection Molding

Injection molding is a production technique that involves shaping materials like plastics, metals, glasses, elastomers, and polymers by injecting the heated substance into a mold. This approach is typically applied in producing simple enclosures such as those found in car remote controls, TV remotes, game controllers, kiosks, displays, calculators, and similar items.

3D Printing

3D printing is an additive manufacturing method that builds enclosures by sequentially adding material layers based on CAD files. This facilitates the creation of complex designs that may be challenging or impossible with other methods such as injection molding.

Both plastic and metal can be utilized in 3D printing, although most 3D printers operate at a slower pace compared to traditional manufacturing methods. It's beneficial for producing small batches, custom enclosures with unique designs, or for prototyping models prior to scaling up for mass production.

Key Design Considerations for Electronic Enclosures

When developing electronic enclosures, several key elements need to be considered, including:

Product Requirements

Product requirements define an electronic product's must-have features, functions, and operational attributes, typically detailed in a Product Requirements Document (PRD). This document offers guidelines on how the product should perform.

The PRD aids in designing an enclosure that meets these specifications. It may specify functions like heat management, moisture resistance, vibration absorption, LED visibility, and fan compatibility. By referring to the PRD, designers can determine the right materials, costs, and manufacturing processes required for the enclosure.

Modeling the Internal Components

Optimal enclosure design requires a comprehensive understanding of internal component arrangement, involving insights into circuit design and electronic layout. For example, holes should be positioned appropriately, and spaces should be allocated for heat or ventilation if heat-sensitive components are present.

Some components should not be placed close to one another due to reasons like interference, erroneous readings, short circuits, or overheating, all of which can reduce their lifespan. Considering these factors is crucial for effective design. Consulting with or hiring experts in this field is advisable for the best results.

Designing the Enclosure Shell

Once internal components are modeled, the enclosure shell can be designed by considering the component arrangement. Before choosing a manufacturing process, creating a 3D CAD model of the enclosure is crucial. This allows for any necessary adjustments or realignment before production begins.

Wall thickness is a critical factor in enclosure design. If walls are too thin, the enclosure may not withstand harsh conditions. Conversely, excessively thick walls might trap heat, potentially jeopardizing the device's functionality.

Comparing the CAD Model with the BOM

Before moving forward with the actual production of the enclosure, comparing the CAD model with the Bill of Materials (BOM) is crucial to avoid any misunderstandings. This comparison can be conducted efficiently using specialized software tools.

Chapter 2: What are the types of electronic enclosures?

Electronic enclosures can be categorized based on the material used and their specific applications.

Classification According to Material Type

Electronic enclosures are typically made from either metals or plastics, resulting in two common types: metal enclosures and plastic enclosures.

Metal Enclosures

Metal enclosures are commonly used in buildings for various applications, such as fuse boxes and meter boxes. These enclosures are designed to protect internal components from accidental impacts, contamination from dust and dirt, and other hazardous conditions. They are typically chosen for applications where portability is not a major concern.

In industrial settings, metal enclosures offer robust protection for equipment, creating a safe and effective working environment. Given the high levels of dirt and debris in industrial environments, metal enclosures are particularly suitable because of their strength and durability, making them ideal for withstanding harsh conditions.

Metal enclosures are available in a wide range of sizes, tailored to their specific applications. For instance, in substations where electrical and power distribution occurs, large enclosures are commonly used. Conversely, smaller metal enclosures are found in consumer devices like light switch fixtures. These enclosures can come in various shapes, including box, cylindrical, and rectangular cylindrical forms, depending on their intended use and the manufacturer's capabilities for metal punching and fabrication.

Aluminum Enclosures

Aluminum enclosures are designed to safeguard electronic components from various types of damage, including electromagnetic interference. These enclosures are suitable for both indoor and outdoor use, protecting devices from adverse weather conditions such as excessive heat, moisture, UV radiation, as well as from dust and dirt contamination.

Exposure to such conditions can lead to electromagnetic interference and other circuit disruptions. Consequently, many electronic devices, including computers, are housed in unibody aluminum enclosures to ensure durability and protection. Aluminum enclosures are also commonly used in handheld devices like remotes, power switches, electrical conduits, garage door openers, and car starters.

Design of Aluminum Enclosures

Designing aluminum electronic enclosures involves comprehending:

• Material Type: Aluminum enclosures are made from aluminum, although other materials can be used for enclosures. Aluminum has different alloys, which are applied differently to these enclosures depending on the use and type of environment the device is exposed to.
• Size and Shape: Most of the aluminum enclosures have a box-like shape with corresponding dimensions but in general, they have lengths ranging from 10 cm to 20 cm. Other different dimensions can be used depending on the specific design of the enclosure.
• Door Type: These types of enclosures usually have a hinged solid lid door. A hinged door can be used where security is needed the most to lock the enclosure. In other enclosures, there are internal gaskets used as well continuous flanges for complete closure of the box and this protects the device from dirt, dust, and moisture. Sometimes the doors are made from the bezel and corner screws, especially when a tight closure is required. These methods of closing aluminum enclosures can be combined for an effective enclosure if need be.

Stainless Steel Enclosures

Stainless steel, composed of iron combined with chromium and occasionally nickel, is known for its corrosion resistance. Often regarded as an eco-friendly material due to its recyclability, stainless steel enclosures are used to safeguard electronic components in both indoor and outdoor settings. While their designs and manufacturing processes are similar to other materials, differences in properties such as density, resistance to corrosion, and cost set them apart.

Plastic Enclosures

Plastic enclosures are containers designed to shield and house electronic components. Typically molded into various shapes to meet product specifications, plastic materials offer flexibility and are lightweight, making them ideal for creating portable devices.

In cases where insulation is required, plastic enclosures are usually the best to use. Common examples of plastic enclosures are found in calculators, remote controls, desktop computers, laptop computers, wireless internet controllers, coolers, game controllers, and televisions.

Design of Plastic Enclosures

When designing plastic enclosures, several factors need to be considered:

Plastic Material Type

A variety of plastic materials can be used for electronic enclosures, with some being used alone while others may be combined. The choice of plastic depends on the specific requirements of the application. For more demanding uses, high-density polyethylene (HDPE) is often selected due to its robustness as a thermoplastic material.

HDPE is valued for its resistance to cold, liquids, and corrosion, its durability, resistance to high temperatures, and its cost-effectiveness in production. Other plastics used include acrylic, polyvinyl chloride (PVC), polypropylene, acrylonitrile butadiene styrene (ABS), styrene ethylene butadiene styrene (SEBS), and polyamide (PA).

Here are some commonly used materials for manufacturing plastic electronic enclosures:

• Acrylonitrile Butadiene Styrene (ABS): Acrylonitrile Butadiene Styrene is used to manufacture plastic enclosures and is very effective, especially when used in environments where resistivity to chemicals is required and shielding from impacts. ABS has poor resistivity to ultraviolet (UV) light and is effective for indoor enclosures.
• Acrylonitrile Styrene Acryl Ester (ASA): Acrylonitrile Styrene Acryl Ester is used in applications such as food manufacturing, healthcare, pharmaceutical or laboratory facility, wellness because of its antimicrobial properties. In environments where there are fungi and viruses, ASA is well protected and can be mounted in bacteria-prone areas.
• Combination of Polycarbonate and Acrylonitrile Styrene Acryl Ester: Sometimes the best electronic enclosures are brought about by combining the different properties in materials to bring the best enclosure. When Polycarbonate is combined with Acrylonitrile Styrene Acryl Ester, this enables the enclosure to have flame resistance, withstand high temperatures, ensure resistance to weather and chemicals, survive in impact-ridden environments, and make the product usable for outdoor environments. Many properties can be attained but combining materials and such enclosures is usually expensive and durable.
• Carbon Neutral Bioplastic: Carbon Neutral Bioplastic is a new type of plastic that is biodegradable. These types of materials are used where there is a need for soft case enclosures. They are naturally occurring, and they are certified biodegradable.

Enclosure Classification According to Application

Enclosures can also be classified according to their application. Some of them are:

Computer Enclosures

Computer enclosures are designed to safeguard computer hardware from potential damage and contamination caused by dirt, moisture, and dust. These protective cases are crucial in ensuring the longevity and functionality of computer components. Today, computer enclosures are prevalent in a wide range of environments including homes, offices, spacecraft, vehicles, factories, and even portable devices like bags and pockets.

Computer enclosures are designed based on the environment in which the computer is going to operate, for example a home computer is exposed to dust, exposure to liquids, and impacts from the accident. A computer used for industrial purposes is exposed to the same impacts but to a greater extent. In heavy manufacturing industries computer enclosures are supposed to be designed to protect the computer from flying debris, unwanted temperature ranges, and protection from moving machinery and workers.

Design of Computer Enclosures

When designing a computer case, the following factors should be taken into account:

Computer Enclosure Intended Use

Enclosures for computers used in vehicles need to be engineered to protect against vibrations and impacts caused by driving and engine operations.

Computer enclosures, including those for laptops, should be constructed from lightweight materials for easy portability while still being durable enough to withstand accidental impacts.

Computer Material Type

Computer enclosures are crafted from various materials based on factors such as application, cost, and durability. Common metals used include aluminum and stainless steel, particularly when portability and weight are less of a concern. In contrast, many laptops feature enclosures made from lighter metals or plastics like ABS (acrylonitrile butadiene styrene) to enhance portability.

The National Electronics Manufacturers Association (NEMA) aids electronic manufacturers by offering ratings that help determine the suitability of enclosure materials for different applications. These ratings indicate whether an enclosure is appropriate for indoor or outdoor use. For instance, ratings such as 1, 2, 12, 12K, and 13 are designed for indoor environments with minimal contamination risk. NEMA provides guidance on enclosures for both low and high hazard conditions, whether indoor or outdoor.

Custom Enclosures

Custom enclosures are developed when standard electronic enclosures do not meet specific or unique requirements. These enclosures are created from the ground up, beginning with a design concept tailored to fit the exact needs of the application.

Essentially, a custom electronics enclosure is a carefully crafted solution that matches the precise dimensions and components required for the space. Often made from plastic to meet specific needs like UV protection for indoor use, these enclosures are sometimes based on standard models that are modified to address unique conditions.

While most electronic enclosures have a box-like shape, some applications require irregular or custom shapes. This might involve designing for curves, contours, or other complex geometries. Materials like aluminum, galvanized steel, and stainless steel are frequently chosen for their strength and durability, whereas plastics are typically used for more intricate and small-scale designs.

Portable Enclosures

Portable enclosures are designed to be compact enough to fit in a pocket or be easily held in hand. They are commonly used for devices such as LEDs and battery compartments. Examples of portable enclosures include car key fobs, laptop cases, computer mice, and TV remote controls.

Desktop Enclosures

Desktop enclosures are built to safeguard computers in office or industrial settings from dust and other contaminants. Components such as the Central Processing Unit (CPU) are sensitive, so these enclosures often include features like engravings, footpads, and removable stands to facilitate easy relocation if necessary.

Display Enclosures

Display enclosures, such as those with touch screens and transparent windows, are widely used today. These enclosures shield screens from sunlight, impacts, and liquid spills. They are typically constructed from glass and plastic, as these materials are well-suited for maintaining visibility while protecting colorless displays.

Wall-Mounted Enclosures

Wall-mounted enclosures, as the name suggests, are designed to be fixed to walls while safeguarding electronic equipment from damage, contaminants, heat, and other hazardous conditions. These enclosures are commonly made from a combination of plastic and metal materials.

Cabinet Enclosures

Cabinet enclosures are primarily used to protect equipment related to video and audio production, including cameras and televisions.

NEMA (National Electrical Manufacturers Association) Enclosures

NEMA enclosures are common in many industries such as telecommunication, rain services, bus services, electronics, domestic and commercial appliances, security, aviation, sound and music, defense and rail services. They are seen in nuclear power plants housing the wiring in nuclear reactors and control rooms. NEMA is a group that intends to bring manufacturers together so that they come under the umbrella of expanding markets and increase their profits by reducing manufacturing costs of products.

Materials Used for NEMA Enclosures

NEMA enclosures are commonly constructed from materials like polycarbonate and various steel and aluminum alloys, including 316 stainless steel, 304 stainless steel, and 5022 aluminum powder-coated carbon steel. Polycarbonate, a high-temperature resistant thermoplastic, boasts impact resistance approximately five times greater than fiberglass. It is also resistant to heat, water, impact, and flames, and offers excellent insulation properties. Enclosures made from polycarbonate are suitable for low-temperature environments. NEMA enclosures can be designed in various forms such as junction boxes, free-standing units, troughs, floor mounts, wall mounts, and free-standing designs with leg kits.

EMI Enclosures

EMI, or electromagnetic interference, is also referred to as Radio Frequency Interference (RFI) in electronics. This type of disturbance arises from external sources and can interfere with electrical and electronic circuits and components. EMI enclosures are engineered to shield electronic devices from unwanted interferences caused by electromagnetic fields, radiation, coupling effects, and other potential disruptions. Common sources of electromagnetic interference include toaster ovens, automobile ignition systems, thunderstorms, electric blankets, the sun, and computer monitors. These enclosures prevent interference by blocking, conducting, absorbing, or reflecting electromagnetic energy.

Materials Used for EMI Enclosures

EMI enclosures are typically constructed from various metals, including solid and perforated types. An example is a microwave door, which prevents microwaves from escaping the appliance. Metals such as aluminum, copper, nickel, steel, stainless steel, and their alloys are frequently used to build EMI enclosures. Sometimes, manufacturers apply metal coatings to plastic materials, which still qualifies as an EMI enclosure. These enclosures are used across multiple industries including food and beverage services, telecommunications, stage productions, and healthcare. Everyday devices vulnerable to interference include cell phones, FM radios, televisions, and computers.

Leading Electronic Enclosures Manufacturers and Suppliers

• Tri MAP International, Inc.

• AutomationDirect.com

• Saginaw Control & Engineering

• Accurate Metal Fabricating

• EIC Solutions, Inc.

Chapter 3: What are the benefits of using electronic enclosures?

The advantages of electronic enclosures vary based on the material used. Manufacturers typically use plastic and metal to fabricate enclosures, which are detailed below.

Benefits of Using Plastic Enclosures

Plastic enclosures offer several benefits, including:

Enclosures are Non-Magnetic

Magnetic interference can affect some electronic devices, but plastic enclosures virtually eliminate this risk as they do not produce magnetic fields.

Enclosures are Insulating

Plastic, like rubber, is an insulator and does not conduct electricity. This makes plastic enclosures ideal for applications where avoiding electrical conductivity is crucial, such as covering motherboards and processors in laptops to prevent short circuits.

Plastic Enclosures are Waterproof

Plastic enclosures are resistant to water and can withstand exposure to humid environments, including water, snow, or rain, without sustaining damage. Unlike metal enclosures, they do not suffer from rust when exposed to moisture.

Cost-Effective Plastic

Plastic is an economical material, making plastic enclosures more affordable compared to metal options. This cost-effectiveness makes them a popular choice for many applications.

Plastic Enclosures are Lightweight

The lightweight nature of plastic enclosures makes them particularly suitable for portable electronic devices. Items such as car remotes, game controllers, cell phones, and chargers benefit from this characteristic.

Flexible Enclosures

Plastic enclosures can be easily shaped into complex forms due to their flexible chemical structure, allowing for precise fittings and custom designs.

Benefits of Using Metal Enclosures

Aluminum and stainless steel are commonly used metals for electronic enclosures. This section outlines their benefits, though these advantages extend beyond just these two metals.

Benefits of Aluminum Electronic Enclosures

• They resist corrosion and rusting.
• They block radio frequencies from passing through them.
• They can resist high temperatures.
• The scrap is easily recyclable.
• Aluminum enclosures can resist UV light.
• They are lightweight when compared to steel.

Benefits of Stainless Steel Electronic Enclosures

• They can withstand harsh and rigorous operating conditions.
• They have longevity and can retain their structure and appearance.
• Using stainless steel enclosures will not affect the color, flavor, and odor of food.
• Good hygiene is easy to maintain when using stainless steel.
• They are durable.
• They are cost-effective and fire-resistant.

Considerations When Choosing an Electronic Enclosure

When selecting an electronic enclosure, several factors should be considered:

Environmental Conditions

Electronic devices are integral to many aspects of daily life and are used across various industries. These devices operate in diverse environments, which can range from harsh to mild. Designing an electronic enclosure requires evaluating the specific environmental conditions it will face, such as exposure to sunlight, dust, rain, vibrations, or chemicals. Understanding these conditions will aid in choosing the appropriate material for the enclosure.

Industry Design Standards and Performance

Compliance with industry standards and regulations is crucial when designing electronic enclosures. Organizations like the International Electrotechnical Commission (IEC) and various government bodies set guidelines and specifications that must be adhered to. These standards define the necessary product specifications, and ensuring conformity is essential for creating a functional and compliant enclosure.

Thermal Requirements

Understanding the thermal dynamics of the electronic components being protected is vital. It's important to know the amount of heat generated by the internal components, such as regulators, resistors, LEDs, and power circuits. While plastics are effective insulators, they may melt under high temperatures, so they are best suited for low-heat applications. Metals, on the other hand, are more suitable for enclosures dealing with high heat dissipation.

Types of Materials in Enclosures

Today, various materials can be used for enclosures, with choices influenced by factors like cost, weight, size, and aesthetics. Acrylic is a popular and cost-effective option due to its lightweight, impact resistance, and flexibility. Polycarbonate is also favored for its thermal stability and impact resistance. Other materials such as aluminum, glass, copper, and steel are used depending on cost considerations and specific application needs.

Electromagnetic Compatibility (EMC)

For a system to be electromagnetically compatible, it must meet specific characteristics that ensure proper operation without interference.

• The system does not cause interference to other systems or equipment surrounding it.
• The system should not be affected by emissions from other systems or equipment such as electromagnetic fields created by other circuits.
• The system should not cause interference within itself.

The diagram below illustrates how emissions are distributed in electrical and electronic devices.

Conclusion

The electronic industry is fast-growing, and this is evident especially when we look at the portable electronic devices that almost the whole world has been exposed to. We use devices like cell phones, radios, microwaves, remote control, laptops, etc on a daily basis and the information provided in this article will give either the consumer or the manufacturer of these devices some insight on how best to interact with these electronic enclosures.

Leading Electronic Enclosures Manufacturers and Suppliers

• Tri MAP International, Inc.

• AutomationDirect.com

• Saginaw Control & Engineering

• Accurate Metal Fabricating

• EIC Solutions, Inc.